Parking assist device and parking assist system

ABSTRACT

A parking assist device for assisting parking of a vehicle, includes: a detecting unit that detects whether there is any obstacle and detects available parking areas for the vehicle, on the basis of a taken image of the surrounding area of the vehicle; and a selecting unit that selects an available parking area where the vehicle is parked with low risk of contact with the obstacle, from the detected available parking areas, on the basis of whether there is the obstacle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 15/058,482 filed Mar. 2, 2016, which in turn claims priority under35 USC 119 from Japanese Patent Application No. 2015-071888 filed onMar. 31, 2015. The entire content of these prior applications isincorporated herein by reference.

BACKGROUND 1. Technical Field

The present invention relates to a technology for assisting parking of avehicle.

2. Related Art

In the related art, there is proposed a technology for offeringavailable parking areas for a vehicle to the driver of the vehicle. Inthis technology, for example, the surrounding areas of the vehicle aretaken by cameras, and parking spaces are detected on the basis of thetaken images. Then, the detected parking spaces are displayed on ascreen, whereby available parking areas are offered. The driver canselect a parking area from the offered available parking areas, and parkthe vehicle in the selected parking area. Also, as a technology relatedto the present invention, there is JP-A-2012-1144 for instance.

SUMMARY OF INVENTION

However, according to the technology for merely offering availableparking areas, in a case where there is a plurality of available parkingareas, for example, inexperienced drivers and elderly drivers oftenselect parking areas regardless of “ease of parking” and so on. In thiscase, people whose driving skill levels are not very high consequentlyselect parking areas having high degrees of parking difficulty.

In view of above, at least one embodiment of the present inventionprovides a technology capable of selecting an area where the possibilityof contact with obstacles during parking or when passengers get out ofthe vehicle is low and it is possible to more safely park the vehicle.

[1] At least one embodiment of the present invention provides a parkingassist device for assisting parking of a vehicle, including: a detectingunit that detects whether there is any obstacle and detects a pluralityof available parking areas for the vehicle, on the basis of a takenimage of the surrounding area of the vehicle; and a selecting unit thatselects an available parking area where the vehicle is parked with lowrisk of contact with the obstacle, from the detected available parkingareas, on the basis of whether there is the obstacle.

[2] It may be the parking assist device according to [1], in which: in acase where three or more consecutive parking areas are detected asavailable parking areas, the selecting unit selects an available parkingarea other than outermost areas.

[3] It may be the parking assist device according to [1], in which: in acase where two consecutive parking areas are detected as availableparking areas, the selecting unit selects an available parking areaaccording to the distances between the detected available parking areasand the obstacle.

[4] It may be the parking assist device according to [3], in which: theselecting unit selects an available parking area having a longerdistance from the obstacle, from the detected two available parkingareas.

[5] It may be the parking assist device according to [1], in which: in acase where two consecutive parking areas are detected as availableparking areas, the selecting unit selects an available parking areaaccording to the passenger location condition of the vehicle.

[6] It may be the parking assist device according to any one of [1] to[5], in which: the selecting unit selects an available parking areaaccording to whether there is any obstacle in an area positioned on thefront side of each of the detected available parking areas.

[7] It may be the parking assist device according to [1], in which: forevaluation items which are surrounding conditions of the vehicle,evaluation values representing degrees of parking appropriateness areset in advance, and the selecting unit derives the degree of parkingappropriateness on the basis of evaluation values associated withevaluation items corresponding to each of the available parking areas,and selects an available parking area where the vehicle is parked withlow risk of contact with the obstacle, on the basis of the degrees ofparking appropriateness.

[8] It may be the parking assist device according to [1], in which: forevaluation items which are obstacle conditions, evaluation valuesrepresenting the degrees of parking appropriateness are set in advance,and the selecting unit derives the degree of parking appropriateness onthe basis of evaluation values associated with evaluation itemscorresponding to each of the available parking areas, and selects anavailable parking area appropriate for parking the vehicle, on the basisof the degrees of parking appropriateness.

[9] It may be the parking assist device according to [7] or [8], inwhich: the evaluation values are set depending on the passenger locationcondition of the vehicle.

[10] It may be the parking assist device according to any one of [1] to[9], further including: a route deriving unit that derives movementroutes to the detected available parking areas; and a display controlunit that displays and superimposes the derived movement routes on thetaken image.

[11] It may be the parking assist device according to [10], in which:the display control unit displays and superimposes a movement route toan available parking area for parking the vehicle on the taken image,and does not display and superimpose movement routes to the otheravailable parking areas.

[12] At least one embodiment of the present invention provides a parkingassist system for assisting parking of a vehicle, including: an imagingdevice that images the surrounding area of the vehicle; and the parkingassist device according to any one of [1] to [11].

According to the at least one embodiment of the present invention, sincean available parking area appropriate for parking the vehicle isselected on the basis of where there is any obstacle, it becomespossible to offer an available parking area where the possibility ofcontact with obstacles during parking or when passengers get out of thevehicle is low and it is possible to more safely park the vehicle.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view illustrating the outline of a parking assist system.

FIG. 2 is a bird's-eye view of the surrounding area of a vehicle.

FIG. 3 is a view illustrating an image of the rear side of the vehicle.

FIG. 4 is a bird's-eye view of the surroundings of the vehicle.

FIG. 5 is a view illustrating an image of the rear side of the vehicle.

FIG. 6 is a bird's-eye view of the surrounding area of the vehicle.

FIG. 7 is a view illustrating the relation between passenger locationconditions and available parking areas.

FIG. 8 is a view illustrating an image of the rear side of the vehicle.

FIG. 9 is a bird's-eye view of the surrounding area of the vehicle.

FIG. 10 is a view illustrating an image of the rear side of the vehicle.

FIG. 11 is a flow chart illustrating a process of the parking assistsystem.

FIG. 12 is a view illustrating the outline of another parking assistsystem.

FIG. 13 is a view illustrating the relation between surroundingconditions and evaluation values.

FIG. 14 is a view for explaining parking appropriateness.

FIG. 15 is a view for explaining parking appropriateness.

FIG. 16 is a flow chart illustrating a process of the parking assistsystem.

FIG. 17 is a view illustrating the relation between surroundingconditions and evaluation values.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described withreference to the accompanying drawings.

1. First Embodiment

<1-1. Configuration of Parking Assist System>

A parking assist system according to the present embodiment is a systemfor offering available parking areas where it is possible to more safelypark a vehicle, to the driver of the vehicle, in a case of parking thevehicle an available parking area which is a vehicle parking space.Especially, the parking assist system of the present embodiment is asystem which is usable in a case of parking a vehicle in a parking lot,and detects available parking areas on the basis of images taken bycameras mounted on the vehicle, and selects an available parking areawhere it is possible to more safely park the vehicle, in view of whetherthere is any obstacle around each available parking area. Hereinafter,the configuration of the parking assist system will be described.

FIG. 1 is a block diagram illustrating the configuration of a parkingassist system 100. As shown in FIG. 1, the parking assist system 100includes an imaging unit 2, a parking assist device 3, a display 4, anda passenger detecting unit 5.

The imaging unit 2 includes a front camera 21, a right camera 22, a leftcamera 23, and a rear camera 24, as imaging devices, and images theoutside of a vehicle. Each of the cameras 21 to 24 has a wide-anglelens, and performs digital imaging with an angle of view of 180 degreesor more, and transmits data on the taken image to the parking assistdevice 3. The cameras are installed on the front, rear, left, and rightof a vehicle, whereby the imaging unit 2 can take the surrounding areasof the vehicle. Even if the cameras 21 to 24 take distorted images dueto the distortion aberrations of their wide-angle lenses, it is possibleto correct the distorted images to planar images by an image correctionprocess.

The front camera 21 is disposed at the leading end portion of thevehicle, and images the front side of the vehicle. The front camera 21is installed on the so-called front grille of the vehicle, but may beinstalled on the back of the rearview mirror positioned in the vehicleso as to image the front side of the vehicle through the front glass.The right camera 22 is installed in the case of the right wing mirror ofthe vehicle, and images the right side of the vehicle. The left camera23 is installed in the case of the left wing mirror of the vehicle, andimages the left side of the vehicle. The rear camera 24 is installed onthe rear portion of the vehicle, and images the rear side of thevehicle. The rear camera 24 is installed in the vicinity of therear-gate opening lever, but may be installed below the rear spoiler. Inthis case, since the imaging viewpoint becomes high, it is possible toimage the rear side of the vehicle over a longer distance.

Although the parking assist system 100 of the present embodiment hasfour cameras, the present invention is not limited thereto. The parkingassist system may have one or more cameras. For example, the parkingassist system may be configured so as to have the rear camera 24 andperform each process of the present invention such as available parkingarea detection on the basis of a taken image by the rear camera 24.

The parking assist device 3 is an electronic control device whichdetects available parking areas for the vehicle, and selects anavailable parking area appropriate for parking the vehicle, from thedetected available parking areas. The parking assist device 3 includes acontrol unit 31, an input/output unit 32, and a storage unit 33.

The control unit 31 is a computer having a CPU, a RAM, and a ROM (notshown). The control unit 31 is connected to the input/output unit 32 andthe storage unit 33 included in the parking assist device 3, andperforms data communication with them, thereby controlling the whole ofthe parking assist device 3. Also, the control unit 31 includes adetecting unit 31 a, a display control unit 31 b, a selecting unit 31 c,and a route deriving unit 31 d. These units included in the control unit31 are functions which the CPU can implement by performing arithmeticprocessing according to programs.

The detecting unit 31 a performs a process of detecting parking framesreflected in images of the outside of the vehicle taken by the imagingunit 2 and detecting parking areas and available parking areas. The term“parking frame” means a frame line defining a vehicle parking space.Also, the term “parking area” means a vehicle parking space surroundedby a parking frame, and the term “available parking area” means aparking area where there is no obstacle such as another vehicle and itis possible to park the vehicle.

The detecting unit 31 a detects parking frames by use of each imagetaken by one or more cameras of the cameras 21 to 24. Specifically, thedetecting unit detects parking frames on the basis of luminance changesin each taken image. This detecting process may be performed withrespect to a predetermined area of each image. The term “predeterminedarea” means, for example, an area of an image corresponding to roadwaysurface. If the detecting process is performed on the whole of eachimage, the processing load becomes huge. However, if the detectingprocess is performed only on a predetermined area, it is possible toreduce the processing load.

Also, the detecting unit 31 a detects parking areas on the basis of thedetected parking frames. Specifically, the detecting unit 31 a detectsareas surrounded by the parking frames, as parking areas. For example,the size of a general parking frame is stored in the storage unit 33,and is compared with the sizes of the areas surrounded by the detectedparking frames, whereby parking areas are detected.

Subsequently, the detecting unit 31 a detects available parking areas.In parking areas where other vehicles have been already parked or thereare any objects, it is impossible to park the vehicle. Therefore, thedetecting unit 31 a detects whether there is any obstacle, and detectsavailable parking areas on the basis of the parking areas and theresults of obstacle detection on the individual parking areas. In short,the detecting unit 31 a performs the obstacle detecting process whiledetecting available parking areas. In this case, the detecting unit 31 adetects parking areas where there is no obstacle, as available parkingareas. Also, obstacle detection can be performed on the basis of eachimage taken by the imaging unit 2. Alternatively, other devices forobstacle detection, such as sensors or radar devices, may be separatelyprovided and detect obstacles.

Also, if parking areas and obstacles are detected, the detecting unit 31a derives distances between the obstacles and parking areas adjacent tothe obstacles, on the basis of the coordinate values of the parkingareas and the obstacles. For example, in a case where an obstacle isanother vehicle, since a distance between the corresponding vehicle anda parking area adjacent to the corresponding vehicle is derived, it ispossible to detect the degree of closeness representing how much thecorresponding vehicle is close to the adjacent parking area.

The display control unit 31 b generates a display image to be displayedon the display 4, and performs display control. The display control unit31 b receives and saves information on the images taken by the imagingunit 2, as a still image or a video file, and converts the imageinformation into data format displayable on the display 4, therebygenerating a display image, and outputs the display image to the display4 through the input/output unit 32. For example, the display controlunit 31 b performs control such that an image of the rear side of thevehicle taken by the rear camera 24 and including parking areas isdisplayed on the display 4.

The selecting unit 31 c selects an available parking area where it ispossible to more safely park the vehicle, from all available parkingareas detected by the detecting unit 31 a, on the basis of thesurrounding conditions of the individual available parking areas (forexample, the results of obstacle detection on adjacent parking areas).This process of selecting an available parking area will be described indetail.

The route deriving unit 31 d derives routes for parking the vehicle inthe available parking areas. Specifically, the route deriving unit 31 dderives movement routes for parking the vehicle in the available parkingareas, on the basis of the location of the vehicle, the locations of theavailable parking areas, the rudder angle of a steering, and the like.Also, the movement routes derived by the route deriving unit 31 d aredisplayed on the display 4 by control of the display control unit 31 b.

The input/output unit 32 controls input/output data related to theparking assist device 3. For example, the input/output unit 32 receivesa signal for requesting start of parking assist control when parking ofthe vehicle starts. Also, the input/output unit 32 outputs a displaycontrol image generated by the display control unit 31 b, to the display4, in response to an output request from the control unit 31. Further,the input/output unit 32 acquires image data transmitted from thecameras 21 to 24 of the imaging unit 2, and so on.

The storage unit 33 retains parking frame information 33 a andparameters 33 b. As the storage unit 33, a non-volatile semiconductormemory which is electrically rewritable and can retain data even ifpower is shut off can be used. For example, the storage unit 33 may beconfigured by an electrically erasable programmable read-only memory(EEPROM) and a flash memory. Also, the storage unit 33 can be configuredby a hard disk drive having a magnetic disk.

The parking frame information 33 a includes information on coordinatevalues and the like representing the parking frames, the parking areas,and the available parking areas detected, and information on coordinatevalues and the like related to the degrees of closeness of theobstacles. Also, the parameters 33 b are various parameters usable inthe detecting process, and are, for example, a predetermined valueusable in edge detection during frame line detection, a predeterminedvalue usable to determine whether an area surrounded by a parking frameis a parking area, and the like.

The display 4 is a display device which has a touch panel 41 anddisplays images and so on. For example, the display 4 is a liquidcrystal display.

The touch panel 41 senses a touch of a user's finger on an area showinga button displayed on the display 4, and outputs information on thesensed position on the touch panel 41 to the input/output unit 32. Fromthe information on the position on the display 4 sensed by the touchpanel 41, and information on the display image generated by the displaycontrol unit 31 b, the control unit 31 can recognize the content of theuser's operation. For example, in a case where the user selects any oneon a vehicle seat position selection screen displayed on the display 4,information corresponding to the selected seat is transmitted to theinput/output unit 32.

The passenger detecting unit 5 detects the seat positions of passengersin the vehicle. In other words, the passenger detecting unit detectswhich seats the passengers are sitting in. Specifically, a method ofproviding sensors below individual seats such that the sensors reacts ifpassengers sit, thereby sensing seats which passengers are sitting in, amethod of providing a camera in the vehicle and sensing which seatspassengers are sitting in, on the basis of a camera image, and variousother methods can be used. Alternatively, the user may register whichseats passengers are sitting in, in advance, by operating the touchpanel 41.

<1-2. Process of Selecting Available Parking Area>

Now, a process of the selecting unit 31 c of the parking assist device 3for selecting an available parking area to be offered to the driver willbe described. This selecting process is a process of selecting anavailable parking area where it is possible to more safely park thevehicle (the risk of contact with other vehicles and the like is low),according to the detected obstacle conditions of the surrounding areasof the individual available parking areas. In the present embodiment,there are first to third selecting processes depending on thesurrounding obstacle conditions. These processes will be described inorder.

First, the first selecting process will be described. FIGS. 2 and 3 areviews for explaining the first selecting process. FIG. 2 is a view forfacilitating understanding of the first selecting process and is abird's-eye view illustrating the surrounding area of a vehicle 1. Also,FIG. 3 is a view illustrating an image taken by the rear camera 24 anddisplayed on the display 4.

The first selecting process is a process of selecting an availableparking area having left and right adjacent parking areas where there isno obstacle such as other vehicles. In other words, the first selectingprocess is a process of selecting an available parking area other thanthe outermost areas in a case where there are three or more consecutiveareas as available parking areas. Hereinafter, the first selectingprocess will be described specifically.

On the basis of information on the coordinate values and the like ofavailable parking areas detected by the detecting unit 31 a, the parkingassist device 3 determines the locations of the available parking areas.In a case where there are three or more consecutive available parkingareas, the parking assist device selects an available parking area otherthan the outermost available parking areas. In the example of FIG. 2,first, if the driver tries to back the vehicle 1 for parking the vehiclein a parking lot, the detecting unit 31 a detects five available parkingareas PA1 to PA5 existing on the rear side of the vehicle 1.

Then, on the basis of the locations of the detected individual availableparking areas PA1 to PA5, the selecting unit 31 c determines whetherthere are three or more consecutive available parking areas in line. Inthe example of FIG. 2, there are three consecutive available parkingareas PA1 to PA3. Therefore, the selecting unit 31 c selects theavailable parking area PA2 other than the outermost areas (that is, thecenter area), as an available parking area where it is possible to moresafely park the vehicle.

Also, even in a case where there are four consecutive available parkingareas, the selecting unit needs only to select an available parking areaother than the outermost available parking areas. In other words, theselecting unit needs only to select an available parking area havingleft and right adjacent areas which are available parking areas (anavailable parking area interposed between available parking areas).

Thereafter, it is possible to display a boxed frame line on thecorresponding area on the image taken as shown in FIG. 3 by the rearcamera 24, thereby offering the selected available parking area to thedriver.

As described above, an available parking area adjacent to areas wherethere is no obstacle is selected and is offered to the driver.Therefore, it is possible to park the vehicle 1 in a safer availableparking area where the risk of contact with obstacles such as othervehicles during parking or when passengers get out of the vehicle islow.

Now, the second selecting process will be described. FIGS. 4 and 5 areviews for explaining the second selecting process. FIG. 4 is a view forfacilitating understanding of the second selecting process, and is abird's-eye view illustrating the surrounding area of a vehicle 1. Also,FIG. 5 is a view illustrating an image taken by the rear camera 24 anddisplayed on the display 4.

The second selecting process is a process of selecting an availableparking area according to the distances from obstacles such as othervehicles existing in adjacent parking areas (the degrees of closeness),in a case where there are two consecutive parking areas as availableparking areas. Hereinafter, the second selecting process will bedescribed specifically.

On the basis of information on the coordinate values and the like ofavailable parking areas detected by the detecting unit 31 a, the parkingassist device 3 determines the locations of the available parking areas.In a case where there are two consecutive available parking areas, theparking assist device derives the distances from obstacles (othervehicles) existing in parking areas adjacent to the individual availableparking areas. Then, the selecting unit 31 c selects an availableparking area having a larger distance (that is, an area having a lowerdegree of closeness).

In the example of FIG. 4, first, if the driver tries to back the vehicle1 for parking the vehicle in a parking lot, the detecting unit 31 adetects five available parking areas PA6 to PA10 existing on the rearside of the vehicle 1.

Then, on the basis of the locations of the detected individual availableparking areas PA6 to PA10, the selecting unit 31 c determines whetherthere are two consecutive available parking areas in line. In theexample of FIG. 4, there are two consecutive available parking areas PA6and PA7, and the selecting unit 31 c selects the available parking areaPA7 farther from an obstacle.

Specifically, on the basis of information on the detected parking areasand the result of obstacle detection, the detecting unit 31 a derivesthe distances between the individual available parking areas andobstacles (the degrees of closeness). In other words, the detecting unit31 a derives the distance between the available parking area PA6 andanother vehicle 10 parked in the adjacent parking area PA11. Also, thedetecting unit 31 a derives the distance between the available parkingarea PA7 and another vehicle 10 parked in the adjacent parking areaPA12.

Then, the selecting unit 31 c compares the derived distances, andselects an available parking area having a larger distance (that is, anarea having a lower degree of closeness), as an available parking areawhere it is possible to more safely park the vehicle. In the example ofFIG. 4, since the distance between the available parking area PA7 andanother vehicle 10 parked in the parking area PA12 is larger than thedistance between the available parking area PA6 and another vehicle 10parked in the parking area PA11, the available parking area PA7 isselected.

Thereafter, it is possible to display a boxed frame line on thecorresponding area on the image taken as shown in FIG. 5 by the rearcamera 24, thereby offering the selected available parking area to thedriver.

As described above, even in a case where there are obstacles in adjacentparking areas, an available parking area having a larger distance froman obstacle (that is, an area having a lower degree of closeness) isselected and is offered to the driver. Therefore, it is possible to parkthe vehicle 1 in a safer available parking area where the risk ofcontact with obstacles such as other vehicles during parking or whenpassengers get out of the vehicle is low.

Now, the third selecting process will be described. FIGS. 6 to 8 areviews for explaining the third selecting process. FIG. 6 is a view forfacilitating understanding of the third selecting process, and is abird's-eye view illustrating the surrounding area of a vehicle 1. FIG. 7is a view illustrating the relation between passenger locationconditions and available parking areas to be selected. Also, FIG. 8 is aview illustrating an image taken by the rear camera 24 and displayed onthe display 4.

The third selecting process is a process of selecting an availableparking area depending on the passenger location condition of thevehicle 1 in a case where there are two consecutive parking areas asavailable parking areas and the distances between the available parkingareas and obstacles such as other vehicles existing in adjacent parkingareas (the degrees of closeness) are the same. Hereinafter, the thirdselecting process will be described.

If the parking assist device 3 detects two consecutive available parkingareas PA13 and PA14, similarly in the second selecting process, theparking assist device derives the distances from obstacles existing inadjacent parking areas. Then, the selecting unit 31 c compares the leftdistance and the right distance. In a case where they are the same, theselecting unit acquires information on the passenger location conditionfrom the passenger detecting unit 5, and selects an available parkingarea corresponding to the passenger location condition.

FIG. 7 shows the correspondence relation between patterns in whichpassengers sit in a vehicle having four seats of the driver's seat, thefront passenger seat, the rear right seat, and the rear left seat andavailable parking areas to be selected. A mark “◯” represents that apassenger is sitting in a corresponding seat, and a mark “x” representsan available parking area to be selected. A table representing thatcorrespondence relation may be stored in the storage unit 33 of theparking assist device 3 in advance. On the basis of the informationacquired from the passenger detecting unit 5 and the table shown in FIG.7, the selecting unit 31 c selects an available parking area associatedwith the passenger location condition.

For example, if determining that passengers are sitting in the driver'sseat, the front passenger seat, and the rear left seat, on the basis ofthe information acquired from the passenger detecting unit 5, theselecting unit 31 c selects the right available parking area (in theexample of FIG. 6. the available parking area PA14). Meanwhile, ifdetermining that passengers are sitting in the driver's seat and therear right seat, on the basis of the information acquired from thepassenger detecting unit 5, the selecting unit 31 c selects the leftavailable parking area (in the example of FIG. 6. the available parkingarea PA13).

In the present embodiment, as an example, the selecting unit comparesthe number of passengers sitting in the right seats of the vehicle (thedriver's seat and the rear right seat) with the number of passengerssitting in the left seats of the vehicle (the front passenger seat andthe rear left seat), thereby determining an available parking area to beselected. In a case where the number of passengers of the right seats islarger, the selecting unit selects the left available parking area;whereas in a case where the number of passengers of the left seats islarger, the selecting unit selects the right available parking area.Since a selection is made such that an area having no obstacles ispositioned on the side where there are more passengers, it becomespossible to avoid contact with other vehicles as much as possible whenpassengers get out of the vehicle after parking.

Also, in the present embodiment, in a case where the number ofpassengers of the right seats and the number of passengers of the leftseats are the same, the selecting unit selects the right availableparking area. The reason is that it is considered that the possibilitythat the driver is accustomed to open and close the door when gettingout of the vehicle is high and thus it is safer to make a selection suchthat an area having no obstacles is positioned on the front passengerseat side. However, the available parking area on the opposite side maybe selected.

For example, in a case where the right available parking area (theavailable parking area PA14 of FIG. 6), it is possible to display aboxed frame line on the corresponding area in the image taken as shownin FIG. 8 by the rear camera 24, thereby offering the selected availableparking area to the driver.

As described above, in a case where there are obstacles in adjacentparking areas, if the distances from the individual obstacles are thesame, an available parking area corresponding to the passenger locationcondition is selected. Therefore, it is possible to park the vehicle 1in a safer available parking area where the risk of contact withobstacles such as other vehicles during parking or when passengers getout of the vehicle is low.

Although FIG. 7 illustrates, as an example, the four-seater vehiclehaving four seats, even with respect to vehicles having differentnumbers of seats, such as five-seater vehicles and seven-seatervehicles, similar tables can be applied. The individual tables may bestored in advance such that it is possible to use a table according tothe number of seats of each vehicle.

Also, as the results of the first to third selecting processes, aplurality of available parking areas which can be selected may exist. Inthis case, all available parking areas may be selected, or any otherselection condition may be added.

For example, a condition on whether there is any obstacle in an areapositioned on the front side of each available parking area may be addedto the selection condition. Specifically, there is a method of adding acondition on whether there is another vehicle parked in an area facingeach available parking area, to the selection condition, in a case ofparking the vehicle in a parking lot where there is a plurality ofconsecutive parking areas on each of the left side and the right side asshown in FIG. 9. In this case where a condition on whether there isanother vehicle in a parking area facing each available parking area isadded to the selection condition, according to the result thereof, anavailable parking area to be selected is determined.

As an example, FIG. 9 will be described specifically. In a case wherethere are four consecutive available parking areas, since there are twoavailable parking areas (PA15 and PA16) other than the outermost areas,in the first selecting process, both available parking areas areselectable.

Then, the selecting unit determines whether there is another vehicleparked in each of the parking areas (PA17 and PA18) facing theindividual available parking areas, and selects an available parkingarea facing a parking area where there is no vehicle. In other words,the selecting unit 31 c determines whether each of the facing areas isan available parking area, and selects an area facing an availableparking area. In the example of FIG. 9, since there is no vehicle in theavailable parking area PA17 and there is another vehicle in theavailable parking area PA18, the selecting unit 31 c finally selects theavailable parking area PA15 facing the area where there is no vehicle.

Also, in a case where there is a plurality of available parking areaswhich can be selected, if all of areas facing the selectable areas areavailable parking areas, since the selectable areas are on par with eachother, both areas may be selected.

Also, while a boxed line is displayed on the selected available parkingarea, a guide line may be displayed on the image at a positioncorresponding to a movement route to the selected available parkingarea. As a result, the driver can grasp not only the location of theavailable parking area but also the movement route to the availableparking area. Further, in a case where the number of selected availableparking areas is two or more, guide lines may be displayed on the imageat positions corresponding to all of the movement routes to the selectedavailable parking areas.

For example, in the example shown in FIG. 9, if both of the availableparking areas PA15 and PA16 are selected, guide lines are displayed onthe image at positions corresponding to the movement routes to theindividual available parking areas PA15 and PA16.

In this case, in a case where the user selects any one available parkingarea, it may be possible to eliminate all guide lines except for theguide line to the selected available parking area. Also, in a case wherewhich available parking area the vehicle 1 is heading is estimated onthe basis of the traveling direction of the vehicle, it may be possibleto eliminate all guide lines except for the guide line to the estimatedavailable parking area.

<1-3. Process of Parking Assist System>

Now, a process of the parking assist system 100 will be described. FIG.11 is a flow chart illustrating the process of the parking assist system100.

The parking assist system 100 starts up if the vehicle is ready forparking, for example, if the vehicle gets into reverse gear. Even in acase where the user turns on a parking assist start switch, the parkingassist system starts up. If starting up, the parking assist system 100detects available parking areas in STEP S101. In other words, theparking assist system detects parking frames, for example, on the basisof a taken image by the rear camera 24, as described above, therebydetecting parking areas. Then, the parking assist system detectsobstacles, and detects available parking areas on the basis of theresult of obstacle detection.

In STEP S102, the parking assist system 100 determines whether three ormore consecutive available parking areas have been detected in theprocess of detecting available parking areas. The parking assist system100 makes a determination on consecutiveness on the basis of thecoordinate values and the like of the available parking areas.

In a case where there are three or more consecutive areas as availableparking areas (“Yes” in STEP S102), in STEP S103, the parking assistsystem 100 performs the first selecting process. In other words, theparking assist system selects an available parking area other than theoutermost areas of the consecutive available parking areas.Subsequently, in STEP S109, the parking assist system 100 displays aboxed line on the image taken by the rear camera 24, at a positioncorresponding to the selected available parking area.

In contrast, in a case where there are not three or more consecutiveareas as available parking areas (“No” in STEP S102), in STEP S104, theparking assist system 100 determines whether there are two consecutiveareas as available parking areas. In a case where there are twoconsecutive areas as available parking areas (“Yes” in STEP S104), inSTEP S105, the parking assist system 100 determines whether thedistances between the individual available parking areas and obstaclesof adjacent areas (the degrees of closeness) are the same as each other.For example, in order for this determination, the parking assist systemcan derive the distances on the basis of the coordinate values of theparking frames or the available parking areas and the coordinate valuesof the obstacles detected on the basis of the taken image by the rearcamera 24.

In a case where the distances between the individual available parkingareas and the obstacles are not the same as each other (“No” in STEPS105), the parking assist system performs the second selecting process.In other words, the parking assist system 100 compares the distances andselects an available parking area having a larger distance.Subsequently, in STEP S109, the parking assist system 100 displays aboxed line on an image taken by the rear camera 24, at a positioncorresponding to the selected available parking area.

Meanwhile, in a case where the distances between the individualavailable parking areas and the obstacles are the same as each other(“Yes” in STEP S105), the parking assist system performs the thirdselecting process. In other words, the parking assist system 100 selectsan available parking area corresponding to the passenger locationcondition of the vehicle. Subsequently, in STEP S109, the parking assistsystem 100 displays a boxed line on an image taken by the rear camera24, at a position corresponding to the selected available parking area.

Meanwhile, in a case where two consecutive areas have not been detectedas available parking areas (“No” in STEP S104), in STEP S108, theparking assist system 100 determines whether one available parking areahas been detected. In a case where one available parking area has beendetected (“Yes” in STEP S108), in STEP S109, the parking assist system100 displays a boxed line on the image taken by the rear camera 24, at aposition corresponding to the detected available parking area.

Meanwhile, in a case where any available parking area has not beendetected (“No” in STEP S108), the parking assist system 100 finisheswithout performing processes such as selection and offering of anavailable parking area.

Also, in the flow chart shown in FIG. 11, in a case where twoconsecutive areas are detected as available parking areas, the parkingassist system performs the second selecting process or the thirdselecting process depending on the distances from obstacles. However,the present invention is not limited thereto. For example, regardless ofthe distances from obstacles, the parking assist system may perform onlythe third selecting process. In other words, in this case, regardless ofthe distances from obstacles, an available parking area is selectedaccording to the passenger location condition.

Also, the flow chart shown in FIG. 11 may additionally include a processhaving a selection condition on whether there is any obstacle in an areapositioned on each available parking area. In this case, after the firstselecting process of STEP S103, the second selecting process of STEPS106, or the third selecting process of STEP S107, the parking assistsystem 100 performs a process of determining whether there is anyobstacle in each of facing areas positioned on the front sides ofavailable parking areas, and selects an available parking area facing anarea where there is no obstacle. Subsequently, in STEP S109, the parkingassist system 100 displays a boxed line with respect to the selectedavailable parking area.

Also, the flow chart shown in FIG. 11 may additionally include a processof displaying a guide line on the image at a position corresponding tothe movement route to the selected available parking area. In this case,after an available parking area is selected, the parking assist systemmay display a guide line together with a boxed line on the image.Further, it is possible to add a process of displaying only a guide lineto an available parking area where the driver tries to park the vehicle,in a case where a plurality of available parking areas is selected and aplurality of guide lines is displayed. In this case, if an availableparking area for parking is determined by a user's instruction or anavailable parking area where the driver is trying to park the vehicle isdetermined on the basis of the result of estimation on the travelingdirection of the vehicle, the parking assist system may perform aprocess of eliminating all guide lines except for the guide linerepresenting the movement route to the determined available parkingarea.

1. Second Embodiment

Now, a second embodiment will be described. In the first embodiment, theconfiguration for selecting an available parking area to be offered tothe driver on the basis of the sequence of detected available parkingareas and the passenger location condition has been described. However,the present invention is not limited thereto. For example, a parkingassist system may be configured so as to retain evaluation valuesrepresenting the degrees of parking appropriateness according to thesurrounding conditions such as whether there is any obstacle, andquantify the degrees of parking appropriateness of individual detectedavailable parking areas on the basis of the evaluation values, andselects an available parking area to be offered to a driver on the basisof the result of quantification. Hereinafter, this configuration will bedescribed with focus on the differences from the first embodiment.

<2-1. Configuration of Parking Assist System>

FIG. 12 is a block diagram illustrating the configuration of a parkingassist system 200 according to the present embodiment. Similarly in thefirst embodiment, the parking assist system 200 according to the presentembodiment is a system for offering an available parking area where itis possible to more safely park a vehicle to the driver of a vehicle.

As shown in FIG. 12, the parking assist system 200 includes an imagingunit 2, a parking assist device 3, a display 4, and a passengerdetecting unit 5. Among these units, the imaging unit 2, the display 4,and the passenger detecting unit 5 are identical to the componentsdescribed in the parking assist system 100 of the first embodiment, andthus will not be described.

The parking assist device 3 is an electronic control device whichdetects available parking areas for the vehicle, and selects anavailable parking area appropriate for parking the vehicle, from thedetected available parking areas. The parking assist device 3 includes acontrol unit 31, an input/output unit 32, and a storage unit 33.

The parking assist device 3 of the present embodiment is different fromthat of the first embodiment in that evaluation values 33 c are retainedin the storage unit 33 and the selecting unit 31 c selects an availableparking area on the basis of the evaluation values 33 c. The otherconfiguration is the same as that in the first embodiment, and thedifferences will be mainly described below.

The evaluation values 33 c are values representing the degrees ofappropriateness including the degrees of parking difficulty set forevaluation items which are surrounding conditions of the vehicle such asobstacle conditions. On the basis of the evaluation values 33 c, theparking assist device 3 of the present embodiment selects an availableparking area where it is possible to more safely park the vehicle, as anavailable parking area appropriate for parking, from detected availableparking areas.

FIG. 13 is a view for explaining the evaluation values 33 c. As shown inFIG. 13, the evaluation values 33 c are values associated withconditions such as whether there is any obstacle in each surroundingarea, and are values representing the degrees of parking appropriatenessincluding the degrees of parking difficulty under the individualconditions. For example, in the example of FIG. 13, an evaluation valuecorresponding to an evaluation item “THERE IS NO OBSTACLE ON BOTH SIDES”in a case where there is no obstacle in the left and right adjacentareas of an available parking area is “1”, and an evaluation valuecorresponding to an evaluation item “THERE IS OBSTACLE ON RIGHT SIDE” ina case where there is an obstacle on the right side is “2”. As describedabove, in the example of FIG. 13, for an evaluation item of a conditionin which the degree of easiness of parking is high (a condition in whichthe degree of parking difficulty is low), a smaller evaluation value isset. Also, in a case where some evaluation items are the same in thedegree of parking difficulty, for an evaluation item more appropriatefor parking, a smaller evaluation value is set.

Also, the evaluation values shown in FIG. 13 are merely examples, andcan be appropriately changed. Also, it is possible to add otherconditions as surrounding conditions. Further, although the presentembodiment uses an adding system for adding evaluation values associatedwith corresponding conditions, a subtracting system for subtractingevaluation values may be used.

The selecting unit 31 c derives the degrees of parking appropriatenesswith respect to all available parking areas detected by the detectingunit 31 a, on the basis of the evaluation values 33 c, and selects anavailable parking area to be offered to the driver, on the basis of theresult of derivation.

<2-2. Process of Selecting Available Parking Area>

Now, a process of the selecting unit 31 c of the parking assist device 3for selecting an available parking area to be offered to the driver willbe described. This selecting process is a process of deriving the degreeof parking appropriateness on the basis of the evaluation values 33 cset according to the surrounding conditions of the vehicle such aswhether there is any obstacle in the surroundings of each detectedavailable parking area, and selecting an available parking area where itis possible to more safely park the vehicle (the risk of contact withobstacles such as other vehicles is low), on the basis of the result ofderivation.

This will be described specifically with reference to FIG. 14. FIG. 14is a view for facilitating understanding of the process of selecting anavailable parking area, and is a bird's-eye view illustrating thesurrounding area of a vehicle 1.

FIG. 14 shows an example in which five available parking areas PA21 toPA25 have been detected by the same detecting process as that in thefirst embodiment. The selecting unit 31 c determines which surroundingconditions shown in FIG. 13 each available parking area corresponds to,and adds evaluation values associated with the corresponding conditions.

As an example, the available parking area PA21 will be describedspecifically. Since there is an obstacle (another vehicle) in a parkingarea positioned on the left side of the available parking area PA21, andthe distance from the obstacle is a medium distance, evaluation values“3” and “2” are added. Further, since there is an obstacle (anothervehicle) in an area positioned on the front side, an evaluation value“2” is added. Therefore, the degree of parking appropriateness of theavailable parking area PA21 becomes “7” (=3+2+2).

In a case of the available parking area PA22, since there is no obstaclein areas positioned on both sides of the available parking area PA22 andthere is no obstacle in an area positioned on the front side, only anevaluation value “1” is added. In other words, the degree of parkingappropriateness of the available parking area PA22 becomes “1”.

If the degrees of parking appropriateness of the other available parkingareas are derived similarly, the degrees of parking appropriateness ofthe available parking areas PA23, PA24, and PA25 become “6”, “8”, and“10”, respectively. If deriving the degrees of parking appropriatenesswith respect to all available parking areas, the selecting unit 31 cselects an available parking area having the lowest degree of parkingappropriateness (the minimum sum of evaluation values). In the exampleof FIG. 14, the available parking area PA22 is selected.

As described above, in the present embodiment, since the degrees ofparking appropriateness are derived on the basis of the evaluationvalues set for the evaluation items such as whether there is anyobstacle in the surroundings of each detected available parking area, itis possible to park the vehicle 1 in a safer available parking areawhere the risk of contact with obstacles such as other vehicles duringparking or when passengers get out of the vehicle is low.

Also, after an available parking area is selected, similarly in thefirst embodiment, a boxed line is displayed at a corresponding positionon the image taken by the rear camera 24, whereby it is possible tooffer the location of the available parking area to the driver (see FIG.3). However, the present invention is not limited thereto. In order tooffer the available parking area to the driver, a boxed line may bedisplayed at a corresponding position on a bird's-eye view image.Further, in these cases, at positions corresponding to the selectedavailable parking area and the other available parking areas, thederived degrees of parking appropriateness may be displayed,respectively.

Also, in the process of selecting an available parking area, anallowable value may be set in advance. The allowable value is athreshold value for the degree of parking appropriateness and is used toselect an available parking area. For example, the parking assist device3 can use a method of selecting all available parking areas having thedegrees of parking appropriateness equal to or less than the allowablevalue.

This will be described specifically with reference to FIG. 15. FIG. 15is a view for facilitating understanding of the process of selecting anavailable parking area, and is a bird's-eye view illustrating thesurrounding area of a vehicle 1.

FIG. 15 shows an example in which six available parking areas PA26 toPA31 have been detected by the same detecting process as that in thefirst embodiment. The selecting unit 31 c performs a process of derivingthe degrees of parking appropriateness of the detected available parkingareas similarly in the case of FIG. 15. As a result, the degrees ofparking appropriateness of the available parking areas PA26 to PA31become “7”, “1”, “3”, “4”, “7”, and “9”, respectively.

Here, if it is assumed that the allowable value is “3”, the availableparking area PA27 for which the degree of parking appropriateness is“1”, and the available parking area PA28 for which the degree of parkingappropriateness is “3” are selected, and the other available parkingareas are not selected. In other words, the available parking areashaving the degrees of parking appropriateness equal to or less than theallowable value are selected, and the available parking areas having thedegrees of parking appropriateness exceeding the allowable value are notselected.

Even in this case, after the available parking areas are selected, boxedlines may be displayed at corresponding positions on an image taken bythe rear camera 24, and boxed lines may be displayed at correspondingpositions on a bird's-eye view image. Also, the degrees of parkingappropriateness of the selected available parking areas and the degreesof parking appropriateness of the other available parking areas may beadditionally displayed.

<2-3. Process of Parking Assist System>

Now, a process of the parking assist system 200 will be described. FIG.16 is a flow chart illustrating the process of the parking assist system200.

Similarly in the first embodiment, the parking assist system 200 startsup if the vehicle is ready for parking, for example, if the vehicle getsinto reverse gear. Also, even in a case where the user turns on aparking assist start switch, the parking assist system starts up. Ifstarting up, the parking assist system 200 detects available parkingareas in STEP S201. This is the same process as STEP S101 describedabove.

Subsequently, in STEP S202, the parking assist system 200 derives thedegrees of parking appropriateness. This is performed by addingevaluation values associated with evaluation items determined as thesurrounding conditions of each of the detected available parking areas.

Subsequently, in STEP S203, the parking assist system 200 determineswhether any allowable value has been set. In a case where an allowablevalue has been set (“Yes” in STEP S203), in STEP S204, the parkingassist system 200 selects each available parking area having the degreeof parking appropriateness (the sum of evaluation values) equal to orless than the allowable value. Meanwhile, in a case where any allowablevalue has not been set (“No” in STEP S203), in STEP S205, the parkingassist system 200 selects an available parking area having the lowestdegree of parking appropriateness (the minimum sum of evaluationvalues).

Subsequently, in STEP S206, the parking assist system 200 displays aboxed line on an image taken by the rear camera 24, at a positioncorresponding to each selected available parking area. In a case ofdisplaying a bird's-eye view image, the parking assist system displays aboxed line at each corresponding position on the bird's-eye view image,and in a case of displaying the degrees of parking appropriateness, theparking assist system displays the degrees of parking appropriateness atpositions corresponding to the available parking areas, respectively.

Also, the flow chart shown in FIG. 16 may additionally include a processof displaying a guide line on the image at a position corresponding tothe movement route to the selected available parking area. In this case,after an available parking area is selected, the parking assist systemmay display a guide line together with a boxed line on the image.Further, it is possible to add a process of displaying only a guide lineto an available parking area where the driver tries to park the vehicle,in a case where a plurality of available parking areas is selected and aplurality of guide lines is displayed. In this case, if an availableparking area for parking is determined by a user's instruction or anavailable parking area where the driver is trying to park the vehicle isdetermined on the basis of the result of estimation on the travelingdirection of the vehicle, the parking assist system may perform aprocess of eliminating all guide lines except for the guide linerepresenting the movement route to the determined available parkingarea.

3. Modifications

Although the embodiments of the present invention have been describedabove, the present invention is not limited to the embodiments, and canbe modified in various forms. Hereinafter, these modifications will bedescribed. All forms including the embodiments described above and thefollowing forms to be described below can be appropriately combined.

In the above described second embodiment, the evaluation values maydiffer depending on passenger location conditions of the vehicle. FIG.17 is a view for explaining evaluation values according to the presentmodification. As shown in FIG. 17, evaluation values differ depending onpassenger location conditions of the vehicle representing whether thereis a passenger in the front passenger seat. An item “THERE IS PASSENGER”represents a case where there is a passenger in the front passenger seatof the vehicle, and an item “THERE IS NO PASSENGER” represents a casewhere there is no passenger in the front passenger seat of the vehicle.

In the example of FIG. 17, the case where there is a passenger in thefront passenger seat and a case where there is no passenger in the frontpassenger seat are different from each other in evaluation valuescorresponding to items “THERE IS OBSTACLE ON RIGHT SIDE” and “THERE ISOBSTACLE ON LEFT SIDE”. The reason is that, in the case where there is apassenger in the front passenger seat, in order to make it possible forthe passenger in the front passenger seat to safely get off and in, itis preferable to park the vehicle with a space on the left side of thevehicle; whereas in the case where there is no passenger in the frontpassenger seat, in order to make it possible for the driver to safelyget off and in, it is preferable to park the vehicle with a space on theright side of the vehicle.

Also, in each embodiment described above, load location conditions maybe included in the passenger location conditions. In other words,available parking areas to be selected differ depending on which seatsloads are on. Although there is no passenger in a seat, if a load is onthe seat, it is necessary to open and close a corresponding door whenpassengers get out of the vehicle. If an available parking area isselected in view of the load location condition, it is possible tominimize the risk of contact with obstacles such as other vehicles whentaking loads in and out.

Also, in each embodiment described above, an available parking area maybe selected even in view of whether there is any obstacle on the rearside of each available parking area. If obstacles on the rear sides ofavailable parking areas are considered, for example, in a case wherethere is another vehicle parked on the rear side of an available parkingarea, it is possible to minimize the risk of contact with thecorresponding vehicle when opening and closing the back door.

Also, in each above described embodiment, various functions areimplemented in a software wise by arithmetic processing of the CPUaccording to programs. However, some of those functions may beimplemented by electric hardware circuits. Also, conversely, some offunctions which are implemented by hardware circuits may be implementedin a software wise.

What is claimed is:
 1. A parking assist device for assisting parking ofa vehicle, comprising: a detecting unit configured to detect anavailable parking area where no obstacle exists; a selecting unitconfigured to, when two or more available parking areas are detected bythe detecting unit, evaluate the two or more available parking areas onthe basis of possible obstacles existing around the two or moreavailable parking areas and automatically select at least one of the twoor more available parking areas on the basis of a result of theevaluation of the two or more available parking areas; and a displaycontrol unit configured to display a bird's-eye view image andsuperimpose a frame on the at least one of the two or more availableparking areas selected by the selecting unit in the bird's-eye viewimage, wherein the parking assist device is configured to, when two ormore available parking areas on which the frame is superimposed arepresent in the bird's eye view, allow a user to select one of the two ormore available parking areas on which the frame is superimposed.
 2. Theparking assist device according to claim 1, wherein the display controlunit displays degrees of parking appropriateness for each of the two ormore available parking areas in the bird's eye-view image.
 3. Theparking assist device according to claim 1, wherein the display controlunit is further configured to display, in addition to the availableparking areas detected by the detecting device, a guide linerepresenting a movement route to the available parking areas.
 4. Theparking assist device according to claim 1, wherein the display controlunit is further configured to display, in addition to the availableparking areas detected by the detecting device, movement routes to theavailable parking areas, and wherein the parking assist device that isconfigured to, when the at least two or more available parking areas onwhich the frame is superimposed are present in the bird's eye view,allow the user to select one of the two or more available parking areason which the frame is superimposed, allows the user to select one of thetwo or more available parking areas after the display control unitdisplays the two or more available parking areas together with themovement routes.
 5. The parking assist device according to claim 4,wherein the display control unit is configured, after the one of the twoor more available parking areas is selected by the user, not to displaythe movement route to other of the two or more available parking areasthan the one selected by the user.